/* 清除浮动 */
.container:after,
.clearfix:after,
.navbar-nav:after,
.nav-tabs:after,
.row:after {
  display: block;
  content: "";
  clear: both;
}
hr.clear {
  margin:0;
  background:#fff;
  color:#fff;
  visibility:hidden;
  clear:both;
}